Chemical Communication

Chemical signal exploitation in predator prey interactions

Signaling lies at the heart of behavioural and evolutionary ecology, being the primary means by which animals choose mates and socialise. Yet social signals are open to eavesdropping enemies, including predators which may use prey cues to improve their foraging. In Australia, prey naiveté to alien predators is one reason why invasive species have been so devastating, yet we know little of how predators find their prey. Our research aims to develop a new understanding about the exploitation of social signals by both predator and prey. In doing so we aim to generate new theory on the reactive foraging behaviour of predators and use this theory to solve conservation problems.

Chemical camouflage to protect vulnerable prey from alien predators

A remarkable form of chemical warfare underpins predator-prey interactions: prey species evolve to disguise themselves by restricting the chemical cues they emit that assist predators in their hunting. We are turning this concept on its head by falsely advertising prey when they are not present (e.g. prior to nesting periods of endangered colonial shorebirds), using readily-available ‘generic’ odours that are similar to the odours of the prey we wish to protect from predators. The idea is akin to olfactory habituation, but with a twist; after being exposed to prey odour cues but finding no prey, predators will learn to ignore the odour cue (Price & Banks 2012 PNAS). Once birds are nesting, predators will no longer be interested in investigating the smell, both in the location of the scent and elsewhere in their home range. If some predators continue to forage near nests, initially they will be confused by a surfeit of odours – some will be

rewarding but others will not, making it difficult for predators to focus on the rewarding cues. We are first exploring whether predators ‘generalise’ bird odour cues and, therefore, whether a generic odour can be used to protect a suite of prey simultaneously. We’re testing the concept in the Mackenzie Basin, New Zealand in collaboration with researchers from Landcare Research (NZ) to protect endangered shorebirds from introduced ferrets, hedgehogs, stoats and feral cats.